There has conventionally been a railway-train communication apparatus that includes a configuration control unit that has a carrier sense multiple access type interface, a switching hub that has a branch function for a transmission path, and a switch that switches off input and output signals of the switching hub. The railway-train communication apparatus controls a communication state in the up/down directions of the transmission path by connecting or disconnecting the switch and recognizes configuration and connection states of communication equipment within a railway train (for example, see Patent Document 1).
The railway-train communication apparatus disclosed in Patent Document 1 uses the switching hub that connects communication apparatuses in one-to-one communication method to evade a fault and removes a master communication apparatus to prevent communication stop in a car. An object of the railway-train communication apparatus is to improve system reliability.    [Patent Document 1] Japanese Patent Application Laid-open No. 2005-117373